In one known type of ground-effect vehicle, the confinement barrier is formed by the juxtaposition of cells each comprising two flexible walls in the form of conical sectors having their concavity directed towards the interior of the vehicle and forming between them a bell-shaped space which is open at its lower end and which is fed primarily by the gas escaping from the cushion of gas created below the central part of the vehicle.
However, in the case of amphibious hovercraft and marine hovercraft with rigid lateral keels, also known as captive air bubble vessels or surface-effect craft, the use of this type of confinement barrier gives rise to serious problems so far as the rear closure of the gas cushion is concerned. This is because, when the liquid surface over which the vehicle travels is made rough by waves, the cells which close the gas cushion supporting the vehicle at its rear end have a tendency, on account of the fact that their concavity is directed in the direction of travel of the vehicle, i.e. towards the gas cushion, to deliver water towards the interior of their concavity, thus creating a "scooping" phenomenon which, on the one hand, gives rise to increases is resistance to the advance of the vehicle and, on the other hand, leads to considerable stresses in the constituent material of the cell walls which can cause tearing of that material.
In order to avoid this scooping phenomenon, it is also known to use a type of inflatable bag arranged at the rear of the vehicle between its two sides for the rear closure of the gas cushion. Unfortunately, this type of rear closure barrier for the gas cushion does not enable the opposing requirements of as high an impermeability to air as possible and as high a permeability to waves as possible to be satisfactorily reconciled.